Adsorption/desorption reactions between polar gases and certain metal salts, often also referred to as "absorption" or "chemisorption" in technical literature, yield complex compounds which are the basis for efficient refrigeration, thermal storage, heat pump systems and power systems having high energy density. However, energy density, a measure of the quantity of polar gas adsorbed on the salt, which translates into the amount of work or energy which can be stored in a given amount of the complex compound, is only one parameter to be considered in designing commercially attractive systems. Of significance, if not greater importance, are the reaction rates between the gas and the complex compound, which result in the time it takes to adsorb and desorb a given amount of the gas into or from the complex compound. Increased or maximized reaction rates result in increased or improved power that can be delivered by the system, i.e., more energy delivered over a period of time, which translates into greater heating and/or cooling or power capability of the system. Complex compounds formed by adsorbing a polar gas and metal salt are characterized by significant, and typically substantial volumetric expansion during the adsorption reaction. Where the adsorption reaction is allowed to proceed without controlling the reaction product density by restricting the volumetric expansion, the resulting reaction product does not achieve the desired coherent, self-supporting mass. Instead, the product is amorphous and powdery, and the product mass will not support its shape or structure. Moreover, once the complex compound is so formed, the physical characteristic of the desired product is substantially irreversible unless successively desorbed and adsorbed without limited expansion, and the desired structure cannot be achieved by further adsorption or desorption unless the complex compound is desorbed, and thereafter introduced into a volumetrically restricted heat exchanger (reaction chamber) cavity and reacted according to the invention. It is also found that such a volumetrically unrestricted complex compound reaction product has substantially reduced adsorption/desorption reaction rates as compared to reaction products in which the volumetric expansion is limited and the density of the reaction product is controlled during the sorption reaction processes if heat and mass transfer is taken into consideration. In application Ser. No. 931,036 the reaction rates of adsorption and desorption of a polar gas with a complex compound are increased by carrying out at least the initial adsorption reaction under conditions so as to achieve a complex compound having a physical structure different from the unreacted salt, and which is at least partially a physically coherent, cohesive, self supporting mass. Such a reaction product is achieved by optimizing the density of the complex compound by limiting the volumetric expansion of the complex compound formed during the initial adsorption reaction. As further disclosed in my aforesaid applications reaction rates are dependent on the thermal conductivity of the solid as well as its gas diffusivity. In order to optimize or maximize the reaction rates, the optimum balance between the thermal conductivity and porosity (gas transport) to provide for high energy or heat transfer balanced with adequate mass transfer or diffusion of the gas through the solid must be achieved. The specific methods and apparatus disclosed in my aforesaid applications for achieving such results are incorporated herein by reference.